Investable assets worth 1 million comprise 15 percent of the households in Singapore, the highest proportion in the world, said a latest report.

A global wealth report released by the Boston Consulting Group showed the number of million-dollar households in Singapore have increased by almost 33 percent from 2009, a local media reported on Thursday.

Switzerland is the second with 9.9 percent with the second highest proportion of million-dollar of households, followed by 8.9 percent for Qatar, 8.7 percent for Hong Kong and 8.5 percent for Kuwait.

But in terms of sheer numbers, the United States has the largest number of millionaire households at 5.2 million, followed by Japan and China.

The proportion of millionaire households for the world as a whole was about 0.9 percent, but they owned about 39 percent of the world's wealth, up from 37 percent in 2009.

Analysts attribute the surge in the number of millionaires to the strong Singapore dollar and soaring asset prices in the tiny island nation.